Oust inspector's force on ship (10)
I believe the answer is:
dispossess
'oust' is the definition.
(thesaurus)
'inspector's force on ship' is the wordplay.
'inspector's' becomes 'di's' (abbreviation for Detective Inspector).
'force' becomes 'posse' (posse is a kind of force).
'on' means one lot of letters go next to another.
'ship' becomes 'SS' (prefix in ship names eg SS Great Britain).
'dis'+'posse'+'ss'='DISPOSSESS'
(Other definitions for dispossess that I've seen before include "Deprive (someone) of land/property" , "Deprive of land and property" , "Expel" , "Drive out l" .)